1. Field of the Invention
Embodiments of the present invention generally relate to a baffle assembly for confining a plasma in an etching chamber.
2. Description of the Related Art
Plasma processing of semiconductor substrates in the manufacture of microelectronic integrated circuits is used in dielectric etching, metal etching, chemical vapor deposition (CVD) and other processes. In semiconductor substrate processing, the trend towards increasingly smaller feature sizes and line-widths has placed a premium on the ability to mask, etch, and deposit material on a semiconductor substrate, with greater precision.
Etching may be accomplished by applying radio frequency (RF) power to a working gas supplied to a processing region over a substrate supported by a support member. The resulting electric field creates a reaction zone in the processing region that excites the working gas into a plasma. The support member may be biased to attract ions within the plasma towards the substrate supported thereon. Ions migrate towards a boundary layer of the plasma adjacent to the substrate and accelerate upon leaving the boundary layer. The accelerated ions produce the energy required to remove, or etch, the material from the surface of the substrate. As the accelerated ions can etch other components within the processing chamber, confining the plasma to the processing region above the substrate may be beneficial.
Unconfined plasmas may cause etch-byproduct (typically polymer) deposition on the chamber walls and could also etch the chamber walls. Etch-byproduct deposition on the chamber walls could cause the process to drift. The etched materials from the chamber walls could contaminate the substrate by re-deposition and/or could create particles for the chamber. In addition, unconfined plasmas could also cause etch-byproduct deposition in the downstream areas. The accumulated etch-byproduct may flake off and result in particles.
Therefore, there is a need in the art for an improved baffle assembly for confining plasma within a processing region inside the plasma chamber.